Interior telephone equipment



June 1, 1937. R. VARLEY INTERIOR TELEPHONE EQUIMENT Filed Aug. 24, 1955NTOR.

INVE

/Q/c//A/e we fx ATTORNEYS.

June 1, 1937.

R. VARLEY 2,082,130

INTERIOR TELEPHONE EQUIPMENT Filed Aug. 24, 1955 2 Sheets-Sheet 2INVENTOR. l/A/@Lfx ATTORNEYS.

EPHONY.

Patented June l, 1937 UNITED STATES L ulllluv PATENT OFFICE 2,082,130INTERIOR TELEPHoNE EQUIPMENT Application August 24, 1935, Serial No.37,625

24 Claims.

My invention relates to improvements in systems of telephoniccommunication, and it has special reference to interior or inter-oiiicetelephone equipment of a type that is particularly adapted for servicebetween telephone stations in the ofiices of two or more individuals whohave unusually close business relations as, for instance, between theoice of a busy business executive and his private secretary orassistant.

In the conduct of many large business enterprises busy executives mustdepend and rely upon their secretaries or assistants to a large degreeto keep well informed as to all business matters and to take notes,answer questions and supply information of various kinds at any time.Therefore, it is highly desirable to be able to establish telephoniccommunication between the respective oices with ease and expedition andwithout interfering with the work at hand.

One of the objects of my present invention is to improve the telephoneservice between individuals so intimately associated in business, insuch away as to conserve the time and effort of the superior orexecutive head and to provide him with convenient facilities forconducting his business with dispatch and readiness.

Another object of my invention is to provide improved telephonic servicebetween ofce stations of two such closely related individuals, whichwill enable them to have ready and immediate telephonic communication,without the necessity of either one putting aside his current work forthe purpose of picking up and utilizing the usual telephone instruments.

A further object of my invention is to so arrange the interior telephoneequipment that in addition to enabling the use of the regular telephoneinstruments, which are located at more or less specific poin'ts in therespective ofces, as, for instance, at desks or tables, it is possiblethrough the agency of suitable loud-speakers and transmitters, to enablethem to converse without the use of the usual telephone instruments, andfrom whatever position in their ofces they may happen to occupy at themoment, or, at least, from various distributed points therein. A stillfurther object of my invention is to provide simple, eiective andexpeditious means for initiating the setting up of such telephonicfacilities by the mere act of momentarily depressing a push button orgently blowing upon any one of a number of suitable control devices thatmay be conveniently and unobtrusively located at distributed points inan omce, and for subsequently and 5 automatically terminating thetelephonic service after a predetermined time interval so'as not torequire further attention of the parties, unless, perchance, it appearsthat the conversation will not be finished in the time intervalavailable, in which case the period of operation may be readily extendedto whatever time is requisite.

Still another object of my invention is to improve and augment interioror inter-ofiice telephone service, such as that hereinbefore mentioned,by making provisions for acoustically coupling the interior telephonesystem with the subscribers telephone instrument of a public telephonesystem, so that incoming calls can be handled at the branch station insecretarys or assistants oilice, if so desired by the superior.

These and other objects of my invention and features by means of whichthey are attained, will be understood from the following description ofthe accompanying drawings, of which Fig. 1 is a diagrammatic view of oneform of my invention, showing the apparatus as it appears wheninstalled;

Fig. 2 is a diagrammatic view of the circuit connections of the interiortelephone system shown in Fig. 1;

Fig. 3 is a diagrammatic view of the circuit connections of an improvedmodication of my invention, andl Fig. 4 is a detailed view, partiallyvin section and partially in elevation, of the construction of a portionof the equipment shown diagrammatically in Fig. 3.

Referring now to Figs. 1 and 2 of the drawings, the interior telephoneequipment therein shown is adapted for communication between twostations A and B, which for illustrative purposes may represent theoflices of an executive and his secretary or assistant, respectively.The instal- -lation includes a desk set or instrument 2 located atstation A and a desk set or instrument located at station B, aninterconnecting cable 6 including a plurality of conductors foroperatively con,- necting said desk sets 2 and l, and a cable 8furnishing energy to desk set 4 from a source of alternating currentrepresented by the plug I0 of Fig. 1 and marked AC in Fig. 2.

Desk set 2, which is adapted to rest upon a desk or table in the oiliceof station A, comprises a cabinet i2 within which is contained aloudspeaker Il (not shown in Fig. l) which is adapted to be heard whenin operation through the open or screened front wall I6 of the cabinet.Within the cabinet l2 and immediately behind the screen I6 is alsolocated a suspended, swingable diaphragm i8 which, as shown in lFigure2, is

pivotally mounted at 20 and is held against a stop 22 by an adjustablecounterbalance weight 24 carried on an arm 26 flxedly associated withthe floating diaphragm |8. This diaphragm is light in weight and isdelicately suspended in such manner that it may be easily actuatedthrough a limited degree of movement by the simple act of blowing gentlythereon.v The diaphragm carries an electrical contact 28 near its lowerend, which is adapted to make momentary electrical engagement with acooperative stationary contact 30 when swung through a small arc in themanner described.

Also mounted Within the cabinet l2 is a hook lever 32 pivotally mountedat 34 and having its free hooked end 36 projecting outwardly through thefront screened wall of the cabinet for the purpose of serving as asupport fora hand-grip telephone instrument 38 which comprises areceiver 40 and a transmitter 42 which are lxedly spaced at theextremities of the hand grip, as is the customary practice. This handgrip telephone instrument 38 is provided with a suspension member 44which is adapted to be placed over and hung upon the outer end 36 of thehook lever 32. y

For the purposes of my invention, this handgrip telephone instrument 38is hung'upon the hook lever in such a position that the transmitter 42faces outwardly from the cabinet, and, therefore, is in position torespond to speech dlrected thereto. On account of its sensitivity thismicrophone will operate effectively even though the speaker be severalfeet removed therefrom.

As a matter of simplicity of the circuit connections, the receiver 40and transmitter 42 of the hand-grip instrument 38 are not shown inFigure 2 as rigidly connected, but in service this will usually be thecase. When the hand-grip instrument 38 or, as shown in Figure 2, thereceiver 40 is hung on the hook lever 32, said hook lever makes anelectrical engagement withv a lower stationary contact 46, but when thereceiver 40 is removed from the hook lever the spring 48 raises saidlever until it makes engagement with an upper stationary contact 60.

In addition to the provision of a suspended floating diaphragm |8 withinthe desk set 2 of station A, said station may be provided with othersimilar floating diaphragms, such as shown at 52, which may be locatedat various distributed points within the room of station A where theywill be conveniently available for ready use. Also associated with thedesk set 2 of station A is a signal device or indicator 54 which, asshown, is of the well-known meter type, but which may, however, take anyother suitable form.

'Ihe facilities shown and described in connection with station A aremore or less duplicated at station B, although in somewhat differentform, and station B is also provided with certain additional equipmentwhich will presently be described.

In the rst place, it should be understood that the desk set orinstrument 4 at station B comprises a cabinet 60 in which is mounted aloudspeaker 62 (not shown in Fig. 1) which may be heard through thescreened front opening 64 of the cabinet, which is also provided with ahook lever 66 similar in construction and function to hook lever 32previously described with respect to station A. A hand-grip telephoneinstrument 68 having a receiver 10 and a transmitter 12 normally hangson hook lever 66 with the transmitter 12 facing outwardly in readinessfor use. As

shown, the desk set 4 at station B does not contain a suspended,floating diaphragm such as I8 and 82 previously described, but similardiaphragms 14 and 16 are provided at conveniently located points in theroom of station B.

Station B is also provided with various auxiliary control devices whichare conveniently located within the cabinet 60. Among these devices is amotor-operated timing and switching device TS, an electromagnetic relayR of the well-known grab magnet" type and also a battery 18.

The motor-operated timing and switching device TS includes an electricmotor of the wellknown alternating current self-starting synchronoustype, such as is commonly employed in selfstarting electric clocks. Thismotor is diagrammatically represented in Fig. 2 by its field winding anda rotor 82 (shown in dotted lines), which rotor is operativelyassociated through suitable gearing (not shown) to a shaft 84 whichcarries an indicating needle or pointer 86, and upon which is alsomounted a cam 88. The gearing above referred to may be so designed as toproduce any desired degree of gear reduction so that the time requiredfor the indicating needle 86 and the cam 88 to effect one completerevolution may be xed in accordance with the requirements of the serviceunder consideration. An ordinary electric clock motor, of course, is sogeared as to cause the second hand to complete one revolution eachminute, and, for illustrative purposes, let it be assumed that in myinvention the driving mechanism is geared to require a period of oneminute for each complete revolution of the associated cam and indicatingneedle.

Operatively associated with the shaft 84, and driven thereby by anyordinary friction drive, is an arm 80 carrying at its outer end anindicating disk or semaphore 92 which may appropriately be painted red,if desired, to constitute a signal. When the motor mechanism is at rest,this semaphore, if it has been manually reset, occupies a position, asshown in full lines in Fig. 2 and is disposed entirely within thecabinet 60, one wall 84 of which is provided with a slotted opening 88,and is shown diagrammatically in Fig. 2. When the driving motor isoperated to turn the geared cam 88 and indicating needle 86 in thedirection of the arrow, the friction drive at the inner end of thesemaphore arm 90 immediately rotates the semaphore in a correspondingdirection until the signal disk 92 occupies a position shown in dottedlines in Fig. 2 as it comes to rest by reason of the engagement of itsarm 80 with the lower end of the slotted opening 86 in the wall of thecabinet, thus indicating that the motor-driven timing and switchingdevice TS is or has been in operation. Of course, this semaphore signalmay be reset manually whenever desired, in view of its friction driveconnection with the shaft 84.

For the purpose of effecting suitable circuit connections atpredetermined relative times in accordance with my invention, themotor-operated cam 88 is provided with an actuating cam surface 98 andan undercut shoulder |00, and cooperatively engaging with the cam is anoperating arm or nger |02 which is carried by a spring arm |04, one endof which is mounted in an insulating block |06 and the free end of whichcarries an insulating button |08, while another insulating button ||0 ismounted at an intermediate point on said spring arm. 'Ihis spring arm|04, with its associated component parts as just described, serves toactuate a plurality of spring switch contacts ||2, ||4, H6. I|8 and |20,which A iaoeaiso |42 normally held by a spring |44 in the position aremounted on the insulatingV block |06, and constitute the control switchfor regulating and adjusting certain circuit connections of my system.The spring contacts just referred to normally occupy the positions shownin Fig. 2 in which contacts ||6 and ||8 are in electrical engagement,but all of the others are disengaged. Spring contact ||8 is providedwith an extended end |22 which projects into proximity with theinsulating button |08 which is carried by the actuating spring arm |04,a suitable gap being provided between the button |08 and the extendedend |22 so that there is a certain amount of lost motion beforeoperative engagement takes place.

Assuming the driving motor and associated mechanism to be at rest, andthe component parts of the timing and switching device TS to occupy thepositions shown in Fig. 2, if the motor is supplied with alternatingcurrent energy it will immediately start into operation to rotate thecam 88 and needle 86 in a clockwise direction,

thereby causing the nger |02 to ride up theactuating cam surface 98 andthus raise the actuating spring arm |04 with its two insulating buttons||0 and |08. As the button ||0 is raised, it immediately effects anelectrical engagement between the spring contacts ||2 and ||4, but, byreason of the gap previously mentioned between the insulating button |08and the extended end |22 of spring contact ||8, the' engagement ofbutton |08 and arm |22 is delayed until after the engagement of contactsH2 and ||4 is effected. Thereupon, however, spring contacts ||6 and ||8are disengaged, and immediately thereafter spring contacts ||8 and |20are brought into electrical engagement. This sequence of operation has adefinite functional relation to the operation of my invention, as willbe understood as the description proceeds.

In order to warn or signal the party at station B a short interval, often or fteen seconds, for instance, prior to the completion of one fullrevolution, a suitable signal is provided which, as shown, takes theform of a bell |26 which at the proper time is struck by a hammer |28mounted at one end of a bell crank lever |29 which is pivoted at |30 andwhich is provided at its other end with a cam-engaging iinger |32normally held by a spring |34 in cooperative engagement with the cam 88.The relative positions of the cam-engaging fingers |02 and |32 are suchthat the lingers |32 drops oi the undercut shoulder |00 of the cam apredetermined time interval before the shoulder reaches the finger |02.As the shoulder |00 passes from under the iinger |32 the spring |34quickly rotates the bell crank |29 and causes the hammer |28 to strikethe signal bell |26, thus giving the warning above referred to.

The relay R is of the well-known grabmagnet construction, and performsan important function in the control of my system, particularly withrespect to the suspended swingable diaphragms which have already beenset forth as capable of being actuated by blowing gently against them tocause a momentary electrical engagement of their cooperating contactmembers. Such engagement of any one of theseveral suspended floatingdiaphragms is adapted to energize a winding |35 of the grab magnet relayR which is disposed around a magnetic core |36 and which serves, whenenergized, to attract to the respective ends thereof a plurality ofarmature switch arms |38 and |40, respectively. Ar-

.mature switch arm |38 is provided with a contact shown and out ofengagement with a cooperating stationary contact |46. Similarly,armature 'switch arm |40 carries a contact |48 which is normally held byspring |50 out of engagement with stationary contact |52. Both armatureswitch arms |38 and |40 are actuated and drawn toward the respectiveends of the core |36 when the winding |35 is energized to thereby eectthe electrical engagement of the cooperating contacts respectivelyassociated therewith.

The electrical engagement of contacts |48 and |52 connects the winding|35 of the relay R directly across the battery 18, and therefore holdsand maintains the respective armature switch arms in closed position,irrespective of the subsequent action of the suspended swingable dia.phragms. This is important in view of the delicate nature of thesefloating diaphragm control devices, it being only necessary to eiect amomentary and light engagement of the contact members associatedtherewith in order to energize the winding |35 and close the contacts|48 and |52 to establish a holding circuit for the relay.

In addition to the various diaphragm control devices located at bothstations A and B, a plurality of conveniently located push buttons |54are provided at the various stations, any one of which may be utilizedmomentarily to energize the winding |35 of the grab magnet relay R. Oneof these push buttons |54 at each station is convenientlylocated on thetop of the respective desk sets 2 and 4.

The indicating needle 86 of the motor-driven ycam device is located inthe front panel of the d esk set 4 at station B, where it may beconstantly observed by the party using the instrument, thus enabling himto determine when the predetermined time interval of the motor-driventiming and switching device TS will terminate, so that he may eithergovern his conversation accordingly or take the necessary steps toextend the time interval.

Having described the general construction and functions of the variouscomponent parts.of the system, a description of the circuit connectionsand operation will now be set forth.

Assuming that during the conduct of his business, the party at stationA, whom I have for illustrative purposes assumed to be a businessexecutive, desires to speak-with the party at station B, whom I haveassumed to be his private secretary or assistant, he has only to blowgently against the suspended floating diaphragm I8 located within thedesk set 2 to initiate the operation of the motor-driven timing andswitching device TS fora setting up the necessary telephone circuits forconversation. By so doing the suspended diaphragm |8 swings through asmall arc in response to the gentle current of air, and effects amomentary engagement of the cooperating contactsy 28 and 30, therebyimmediately energizing the Winding |35 of the grab magnet relay Rthrough a circuit from one side of the battery 18, including conductor|58, spring contacts ||8 and ||6, conductor |60, energizing winding |35of the relay R, conductors |62, |64, and |66, swingable diaphragm I8,contacts 28 and 30 associated therewith, conductors |68, |10 and |12 tothe other side of the battery. This energizes the winding |35 of therelay R, which immediately draws the armature switch arms |38 and |40to- |48 and establishing a holding circuit from the winding |35 throughsaid contacts, armature |40, conductor |14 and conductor |12 to thebattery. This immediately sets up and maintains a holding circuitthrough the energizing winding |35, so that its subsequent action isentirely independent of further movements of the swingable diaphragm |8.

concurrently therewith, the contacts |42 and |46 associated with thearmature i338 are closed, thus connecting `the alternating current,selfstarting synchronous motor to the source of power marked A. C. Thiscircuit is from one terminal of the power source, through the fieldwinding 80 of the driving motor, conductor |16, conductor |18, contacts46 and |42 of the relay R, armature |38 and conductor |80 to the otherterminal of the source of power. The driving motor, which, as set forthis self-starting in character, immediately starts into operation and, byreason of the reduction gearing previously referred to but not shown,rotates the indicating needle 86 and the cam 88 in aclockwise'direction.

This rotation causes the cam-engaging fingers |32 of the signal bellmechanism and the camengaging finger |02 of the actuating spring arm |04to ride over the operating cam surface 98, and therebybe raised inposition as the cam :otates.'v Accordingly, the bell crank |29, uponwhich Athe hammer |28 is mounted, is thus rotated in a counterclockwisedirection against the action of the spring |34 to set the hammer instriking position. Similarly, as the spring arm |04 is raised, theinsulating button ||0 immediately presses the spring contact ||2 intoengagement with the contact ||4. This action bridges the circuitincluding the contacts |42 and |46 I of the armature switch arm |38associated with relay R, by means of a circuitwhich includes conductor|16, and spring contacts ||2 and ||4, thus establishing a new operatingcircuit for the driving motor, which is independent of the subsequentaction of the relay R.

As the cam 88 continues to rotate, the insulating button |08 at the endof the actuating spring arm 04 is raised through the gap previouslymentioned and engages the extended finger |22 which subsequently raisesspring contact |8 and causes it to disengage spring contact I6, therebyinterrupting the holding circuit of the grab magnet relay R, which isthereby deenergized.

This permits its respective armature switch arms |38 and |40 to berestored by their respective springs |44 and |50 to normal position, andeiects a disengagement of the cooperating contacts |42 and |46, and alsoof the contacts |52 and |48.

The continuing rotation of the cam 88 causes spring contact ||8 to beraised into engagement with spring contact |20 to thereby set up thetelephone circuits between stations A and B. 'I'hese circuits includeconductor |58 from one side of the battery 18, spring contacts ||8 and|20, and conductor |84 to the pivotal point |86 of the-hook lever 66 atstation B, where the circuit divides, one branch including thetransmitter 12, conductor |88, hook lever 32, loud-speaker |4 andconductor |90, and the other branch including hook lever 66,loud-speaker 62, conductor |92, signal device 54 and transmitter 42, andthence after joining conductor through conductors |10 and |12 to theother side of the battery 18. 'I'he necessary telephone circuits arethus established for communication between stations A and B.

progressively indicates the proportion of the timeA cycle which has beenconsumed. The signal device 54 at station A also shows that themotordriven timing and switching 'device TS is in operation and that thetelephone circuits are established and ready for service.

'Ihe party or executive at station A may then converse with the party atstation B without the necessity of using his hands to pick up atelephone instrument and without being obliged to lay down any papers orthe like'upon which he may be working. He merely speaks in his normalconversational tone in the general direction of the transmitter 42,which hangs facing outwardly on his desk set 2. It is unnecessary forhim to be in close proximity to the transmitter as it willsatisfactorily pick up the voice even if the speaker is several feetdistant therefrom in another part of the room.

The party at station B hears the conversation through the loud-speaker62 as it emanates from the desk set 4 through the screened opening 64,and is, in turn, enabled to converse with the party at station A in asimilar manner through the transmitter 12 which is hung facing outwardlyon the desk set 4. The party at station B, therefore, may also conversewithout being requiredto pick up a telephone instrument or lay down thework at hand.

It the conversation occupies a period of time no longer than the timeinterval of the motordriven timing and switching device TS, no furthermanipulation of the system by either party is requisite, and themotor-driven timing and switching device will at the end of its cycleautomatically interrupt the motor and telephone circuits and restore thesystem to normal inoperative condition. This will be accomplished as thecam 88 completes its revolution, thereby dro'pping the cam-engagingfinger |02 from shoulder I |00, thus permitting the several springcontacts of the switching device to resume their normal positions andthereby interrupt the several circuits of the system.

In the event that it becomes apparent that the conversation will not becompleted within the cycle period of the timing and switching device TS,the party at station B, noting from the position of the indicatingneedle 86 on his desk set, that such is the case, may extend the periodof operation and set up a new cycle period by either depressing one ofhis push buttons |54 or by blowing gently against one of the oatingdiaphragms 14 or 16 whichare located in his ofice. In either case, thewinding |35 of the relay R will be energized from battery 18 immediatelyupon the completion of the cycle period of the timing and switchingdevice TS, as will be understood. This will reconnect the driving motorto the source of power and initiate a new cycle of operations analogousto those previously described and which need not be repeated.

As a matter of convenience, it will be unnecessary for the party atstation B to watch the indicating needle 86, as just prior to thecompletion of the rst time cycle or revolution of said needle andassociated cam 88, the signal bell |26 will be operated in the mannerpreviously described, which will warn the party ofthe approach of theend of the cycle period and permit him to initiate a new cycle ofoperations in the manner just referred to, if so desired.

If for any reason the party at station B should not make suitablearrangements for repeating the cycle, the source of current for thedriving motor of the timing and switching device TS will be interruptedat the end of the cycle and the telephone circuits will also be opened.However, the operation may be immediately resumed by either party bymerely again actuating one of the oating diaphragms or one of the pushbuttons, so that as a practical matter the interruption will only bemomentary and will not seriously interfere with the conversation.

Although the operation of the system has been described as beinginitiated by the party at station A through the operation of thesuspended floating diaphragm I8 within the desk set 2, it is evidentthat any of the floating diaphragms, such as 52, for instance, which arelocated at convenient places in the oflice, may be utilized for thispurpose, as will be understood without further description. Moreover,any of the several push buttons, such as |54, for instance, which arelocated in the office, may be similarly employed.

It is unnecessary, therefore, that the party at station A be at his deskto effect the establishment of telephone connections, but he may do sowhile occupying other positions in the ofce, and, by reason of thesensitivity of the transmitter 42, he may talk with station B, eventhough he be located several feet away from the instrument. Similarly,the facilities may be utilized at station B in a similar manner andirrespective of the place in the oiilce which the party may occupy.

Through this improved telephonie service, as described, it isunnecessary for either party to incur the inconvenience of putting asidehis work and picking up the telephone instrument, as has been thepractice in the past. Moreover, if there are visitors in either ofliceand the conversation is of a confidential character, the telephoneinstruments in either oiiice may be picked up and used, therebydisconnecting the loud speaker in that particular office andsubstituting therefor the ear phone or usual receiver.

For instance, if the party at station A desires to exclude visitors fromhearing the conversation, over the loud-speaker, he may merely removethe hand set 38 from its hook lever 32, whereupon the telephone circuitthrough the loud speaker I4 is interrupted by the disengagement of thehook lever from the lower contact 46 while the engagement of the hooklever with the upper contact 50. immediately connects the telephonereceiver 40 in the circuit by means of conductor |94.

If the party at static-n B should happen to be out of his oflice at atime when the party at station A attempts to communicate with him, theoperation of the motor-driven timing and switching device TS will beinitiated and the device will function through its usual cycle andthencome to rest. In so doing, the semaphore signal device 92 will bemoved into its lower warning position, as shown in dotted lines in Fig.2, and thus indicate at station B that a call has been attempted. Theparty at station B, noticing this signal upon his return may then callstation A, in the general manner which has already been described.

Referring now to Figs. 3 and 4 of the drawings, the modification of myinvention in interior telephone equipment, as diagrammaticallyillustrate therein, is in many respects similar in construction andoperation to that previously described, but in accordance therewithcertain new and important features are incorporated which are especiallyuseful for service of the general character hereinbefore indicated.

According to this form of the invention, I have extended the utility ofthe previously described system by making suitable arrangements wherebyit may be acoustically coupled to the usual subscriber's telephoneinstrument of a public telephone system, without in any way interferingwith oraffecting in the slightest the operation of said public telephonesystem. With this arrangement, it is not only possible for parties atthe two stations to have telephonie communication between themselves ina general manner already set forth, but telephone calls may be conductedwith parties on the public telephone system by acousticallyinterconnecting the interior telephone equipment with that of the publicsystem.

As shown in Fig. 3, the system in the main corresponds with that ofFigs. 1 and 2 and includes at station A' a loud-speaker I4', atransmitter 42', a signal device 54', a iioating diaphragm controldevice I8' and a push button I 54', all of which may conveniently behoused in a single cabinet.

Station B is equipped with a loud-speaker 62', a transmitter 12', anelectromagnetically operated relay switch R', floating diaphragm controldevices 14' and 16', a push button |54 and a motordriven timing andswitching device TS'.

The electromagnetic relay switch R.' differs slightly in construction,but not in function, from that previously set forth, more particularlyin that it comprises two magnetic cores |38' with energizing windings|35' therefor. One of the electromagnets is adapted to actuate anarmature switch arm |38', while the other. operates an armature switcharm |40 which, in this particular arrangement, is constructed in theform of a bell crank, which is fixedly secured to or integral with thesuspended swingable or floating diaphragm 14 having a restoring spring24' in lieu of a counterbalance weight, as previously set forth.

The timing and switching device TS' is also similar in construction andfunction to that of Fig. 2, and therefore requires no further detaileddescription to enable a full understanding thereof. It is pointed out,however, that the timing and switching device T'S includes twoadditional spring contacts |96 and |98 and also a manuallyoperatedcontrol lever 200, the function of which will become apparent as thedescription proceeds.

The control lever 200 is pivotally mounted at 202 and its inner endcarries a movable roller 204 in engagement with an extension of thespring contact arm I8', said control lever 200 being normally held by aspring 206 against a stop 208. This control lever is adapted to occupytwo operative positions, as indicated by dotted lines marked X and Y.

In addition to the apparatus previously mentioned as part of theequipment at station B', there is also an acoustical coupling devicedenoted generally by the letter C, together with a desk type telephoneset T which constitutes a part of a public telephone system. Thetelephone set T comprises a base 2|0, a dial mechanism 2I2, a cradle 2|4and a French type telephone instrument F having mounted in fixed spacedrelation at the opposite ends thereof a receiver 2|8 and a transmitter220.

' In order to carry out certain functions of my improved invention, thetelephone desk set T normally rests upon a floating platform 222 (Fig.

4) which is yieldingly positioned within a subbase 224 upon a pluralityof springs 226 in such manner that when the entire desk set, includingthe base 2|0 and the French type telephone instrument F, rests upon thesupporting platform 222, the platform is depressed to its lowermostposition by the total Weight of the desk set. However, when the Frenchtype telephone instrument F is removed from its cradle for use, thefloating platform 222 is raised by the springs 226 to an elevatedposition.

I utilize the movement of the floating platform 222 into the positionsindicated to control certain operations of the system. This isaccomplished by mounting a spring contact 230 upon an insulating block232 which is fixed to the bottom of the platform 222, and in cooperativerelation with said spring contact 230 I provide another similar springcontact 234 which is mounted on an insulating block 236 suitably securedto a stationary portion of the sub-base `224. The arrangement is suchthat when the entire telephone desk set T rests upon the floatingplatform 222 the spring contacts 230 and 234 are out of electricalengagement, while when 'the French telephone instrument F is removedfrom its cradle, the springs 226 raise the floating platform 222 andeffect an electrical engagement between the spring contacts 230 and 236.

Theacoustical coupling device C (Fig. 3) comprises a cabinet, of which afragment or portion of its front inclined panel 246 is shown in section.This panel is provided with suitable openings 262 and 244 located invertical relation and fxedly spaced to correspond with the receiver 2I8and the transmitter 220 of the French telephone instrument F when it isplaced in registry therewith. Immediately below the upper opening 242 isa supporting flange member 246 upon which the French telephoneinstrument rests and by which it is suspended in operative position whenan acoustical coupling is effected. In order to effect such anacoustical coupling or connection between the public telephoneinstrument F and my interior telephone system, an auxiliary transmitter122 is mounted within the cabinet immediately behind the upper opening242 in the front panel, and the loud-speaker 62 is similarly positionedin proximity with the lower opening 244 in said panel.

For control purposes, a switching device S is also provided within thecabinet and comprises a plurality of spring contacts 250, 252, 254 and256. Intermediate the spring contacts 252 and 254 is a movable roller258 pivotally mounted at the end of one arm of a bell crank 260 which ispivoted at 262, and the other end 264 of which is so positioned as to becooperatively engaged by a switchactuating rod 266 which projectsthrough a boss 268 on the front panel 240. This actuating rod carries ahead or button 210 at its outer end by means of which it may bedepressed by the operator to effect the actuation of the bell crank 260against the action of a spring 212, to thereby actuate the springcontacts 250, 252, 254 and 256. The spring 212 normally holds thevarious parts of the enclosed switch S, including the actuating rod 266,in the position shown in the drawings, in which spring contacts 250 and252 are disengaged, while spring contacts 254 and 256 are in electricalengagement.

'I'he head or button 210 of the actuating rod 266 normally occupies aposition such that the French telephone instrument F is prevented frombeing placed in full and efficient acoustical relation with themicrophone 10' and loud-speaker 62' until the actu-ating rod 266 isdepressed to effect the actuation of the various switch contacts. TheFrench telephone instrument F is shown in dotted lines in Fig. 3 in anintermediate and only partially operative understood that in order toeffect a full and eilicient acoustical coupling, the actuating rod 266must be depressed before the telephone instrument can be placed in finalacoustical relation and be supported therein by the supporting flange246. After being depressed the 4actuating rod 266 is held in position bythe telephone instrument F.

Also constituting a coupling device C is a trol switch 214 216 andcarries part of the acoustical manually-operated conwhich is pivotallymounted at on an armature portion 218 thereof a contact 280 normallyheld in cooperative engagement with a stationary contact 282, while itsother end 284 carries an actuating button 286 which convenientlyprojects outside the cabinet and by means of which the operator may movethe control switch 214 against the action of a spring 288. This controlswitch 214 normally forms a part of the telephone circuit betweenstations A' and B', but, when moved by the .operator into inoperativeposition, it disengages the contacts 280 and 282 and interrupts thetelephone circuits. At the same time, the armature portion 218 thereofis moved into electromagnetic relation with an electromagnet 290 havinga core 292 and an energizing winding 294, which is energized wheneverthe French telephone instrument F is removed from its base, as will morefully later appear. When the switch is closed the armature portion 218is not in the field of influence of the electromagnet 290.

As a matter oi' convenience the acoustical coupling switching deviceTS',

and appearance, device C, the timing and the electromagnetic relayswitch R and the suspended floating diaphragm 14' may be contained in asingle cabinet with the floating diaphragm located immediately behind asuitable opening in the front panel where it is suitably positioned tobe actuated by the party at station B.

Before proceeding with a description of the operation of the system, itis important to point out that the public telephone set T, which isutilized in the system of my invention, is preferably of a type now onthe market and which is provided and used in conjunction with a suitablecontrollable electronic amplier'unit, such as is embodied in theso-called hard of hearing telephone equipments.v The adjustableamplifier unit is not illustrated in the drawings and its constructionand .operation forms no part of my invention, except as it performs thefunction of amplifying messages received over the public telephonesystem in order that they may be delivered as articulate speech throughthe receiver 2|8 at amplified or intensified volume, which may beregulated to the personal convenience or requirements of the hearer or,when used in connection with my invention, in accordance with therequisites of the service intended.

0f course, in lieu of utilizing an electronic amplifier unit forintensifying such messages before they emanate as speech from thereceiver position, it being of the public telephone set, and which aresubsequently acoustically transmitted to the interior telephoneequipment, I may nd it desirable in certain instances to employ anordinary public telephone set, which does not include an amplifyingunit, and eiect the necessary amplication in the interior telephoneequipment by incorporating therein a suitable/and adjustable electronicamplifier intermediate the transmitter '|22 and the loud-speaker I4.

Having set forth a description of the construction of certain of theadded parts of this modified form of my invention, an explanation of theoperation of the system as a whole follows, except that,'in view of thesimilarity in operation of the interior telephone equipment with thatpreviously described in connection with Fig. 2, the operation will besummarized to some extent.

Assuming then that the party at station A', whom I have assumed to be abusiness executive, actuates the floating diaphragm |8' (or push button|54'), the electromagnetic relay switch R' is connected across battery'I8' through a circuit which includes conductors 300 and 302, diaphragmcontacts 28 and 30', conductors 304 and 306, to the ,pivot point |4| ofthe combined bell crank |40' and floating diaphragm 14', and thencethrough the respective windings |35' of the relay R', which areconnected in parallel, conductor 3I0, switch arms IIB and H8' andconductor 3|2 to the other side of the battery, The electromagneticrelay R is thus energized and one of its cores attracts the armatureswitch arm |38 to eiect an `electrical engagement between thecooperating contacts |42' and las',

thus establishing the motor circuit of the motor-driven timing andswitching device T'S' from the source of energy marked A. C.' throughthe motor field winding 80', conductor 3|4, conductor 3|6, contacts |46and |42' of the relay R', conductor 3|8 and conductor 320 to the otherside of the source of energy. The driving motor of the timing andswitching device TS' then starts into operation to rotate, throughsuitable reduction gearing, the cam 88 and the indicating needle 84whereby bythe same cycle of operations is carried out, as already setforth in connection with Fig. 2 of the drawings.

Concurrently with the energization of the windings |35'. of the relayR', the other core thereof attracts the armature arm of the bell crank|40 which causes the contact |48', mounted on the other arm thereof, toelectrically engage contact |52', thus establishing a holding circuitfor the relay from the battery 18' which maintains the energization ofthe relay R', irrespective of subsequent movements of the floatingdiaphragm I8. In this way the supply of energy to the driving motor iscontinued even though disengagement of the diaphragm contacts 28' and30' is subsequently effected.

As the motor driven cam 88' rotates in a clockwise direction, the camengaging finger |02 of the actuating spring a'rm |04' is raised by itscooperative engagement with the cam actuating surface 98'. Thus, springcontacts H2' and H4' are engaged to bridge the temporary motor circuitthrough the relay contacts |42 and |46. Subsequently, the energizingcircuit of the relay R' is interrupted by the disengagement of springcontacts H6' and H8 and, immediately following this operation, thespring contact H8 is brought into engagement whereby the teleand withthe spring contact |20' phone circuit interconnecting stations A B isestablished as follows:

The telephone circuit is completed from one side of the battery 18through conductor 3|2, spring contacts H8' and |20', conductor 324,armature switch arm 218 of the control switch 214, contacts 280 and 282and conductor 326, where the circuit divides, one branch includingloud-speaker 62 associated with the acoustical coupling device C,conductor 328, signal device 54', transmitter 42' at station A andconductor 300, while the other branch includes conductor 332, springcontacts 256 and 254 of control switch S, transmitter 12' associatedwith the acoustical coupling device C, conductor 334, and lloudspeaker|4' at station A', from whence the circuit 'joins the circuit previouslyrecited and is completed through conductor 300 to the other side of thebattery. l

Upon the establishment of the telephone circuit, the conversationbetween the parties at station A and B may be carried on throughout thepredetermined time interval of operation of the combined timing andswitching device T'S'. Moreover, this conversation may be carried onfrom whatever points in the respective offices the parties may happen tooccupy, by reason of the sensitive transmitters and the loud-speakingequipment, without the necessity of using the hands and incurring theinconvenience of employing the usual telephone instruments.

As "will be understood, the timingand switching device TS' maintains thetelephone circuit for a predetermined time interval and thenautomatically interrupts the circuit without requiring further attentionby either of the parties. Just prior to the interruption of thetelephone .circuit and the termination of operation of the timing andswitching device T'S', a signal is given by the bell striking lever |29which has a cam-engaging finger |32' on one end and a spring mountedhammer |28' at the other. This hammer |28' strikes the bell |26' whenthe camengaging finger |32 drops off of the undercut cam shoulder |00.

If it is desired by either party to prolong the telephone conversation,a new cycle of operations of the timing and switching device TS may bestarted through any one of the floating diaphragms or push buttons.Alternatively, if the conversation is to be continued for a short periodand it is not desired to initiate a new time cycle of operations, theparty at station B' may maintain the telephone circuit temporarily bydepressing the control lever 200 a slight amount to position X to eithermaintain or even to reestablish electrical engagement between springcontacts IIB' and |20', while permitting the timing and switching deviceT'S' to complete its cycle and cut ofi the source of energy to thedriving motor.

In the event that it appears that the conversation may be prolonged to aconsiderable degree and the operator at station B' finds it inconvenientto hold the control lever 200 in operative position X for more than abrief period, he may initiate another cycle of operations of the motordriven timing and switching device T'S by merely depressing the controllever 200 to a greater degree into position Y whereby an insulatingbutton 336 engages spring contact |96 and forces it upwardly intoelectrical engagement with spring contact |98, thus establishing a shuntor bridging circuit across the disengaged spring contacts H2' and H4 andconnecting the driving motor directly to the source of power. As soon asthe driving motor starts into operation, the timing and switching deviceTS performs its usual functions. It is therefore unnecessary for theoperator to hold down the control lever 200 after the motor beginsoperation.

The operation so far described with respect., o Fig. 3 is in generalquite analogous to that previously set forth in connection with Fig. 2.However, the system of Fig. 3 is adapted for important additionalservice in enabling the interior telephone system to be acousticallyconnected to an outside public telephone system which is accomplishedthrough the agency of the French telephone instrument F and theacoustical coupling device C in the following manner:

Assuming that a telephone call is received on the public telephone setT, the party at station B', whom I have assumed for illustrativepurposes to be a private secretary or assistant to a business executivelocated at station A', picks up the French telephone instrument F toanswer the call. By reason of the decrease in weight of the telephoneset T resting upon the floating platform 222, the spring contacts 230and 234 are brought into engagement. A circuit is thus established fromone side of a source of energy marked AC through a conductor 340, springcontacts 230 and 234, and conductor 342, to a combined audible andvisible signal device 344, or either one, where the circuit divides, onebranch including the signal device 344 and conductor 346 to the otherside of the source of energy, while the other branch includes conductor348, energizing winding 294 of the holding magnet 290, conductor 350,and conductor 346 to the other side of the source of energy.

In this way, the signal device 344 operates at once to indicate that theFrench telephone instrument F of the public telephone system is out ofits cradle, and this signal is maintained until the instrument isrestored thereto. Furthermore, the holding magnet 290 is immediatelyenergized and is therefore ready for use, as will later appear.

If the party or secretary at station B is able to answer the callhimself he does not disturb his superior at station A', and in order toprevent any interference.v with the conversation which might take placeif the party at station A should attempt in the interim to communicatewith him on the interior telephone system, it is only necessary for theparty at B to manually operate the control switch 214 by depressing thebutton 286 thereof to thereby interrupt the telephone circuit bydisengaging contacts 280 and 282. As soon as the control lever 214 is somoved, its armature switch arm 218 thereof is brought into the spehereof action of the holding magnet 290 which, already being energized. asabove explained, magnetically holds the control switch 214 ininoperative position to maintain the interruption of the telephonecircuit between stations A' and B until the French telephone instrumentF is returned to its cradle. Thereupon the added weight of thisinstrument depresses the floating platform 222 and disengages thecontacts 230 and 234 to cut oil the supply of energy to the signaldevice 344 and the holding magnet 290. Thereupon, the control switch 214is automatically re-set to its initial operating position by means ofthe spring 288 and the system is thus restored to a condition for normaluse.

of the control Should it be determined by the party at station B' thatit is desirable for his superior to personally answer the outside call,he merely speaks to his superior on the interior telephone system in themanner already explained, and having ascertained that his superior isready to take the call, it is only necessary for the party at station Bswitch S and thereafter, or inthe act of so doing, the French telephoneinstrument F is placed in operative position upon the acousticalcoupling device C with the receiver 2I8 thereof in acoustical relationwith the auxiliary transmitter 122 and the transmitter 220 thereof inacoustical relation with the loud-speaker 62' of the coupling device.

'Ihe actuation of the control switch S serves to cut out of operationthe transmitter 12' associated with the coupling device C and to replaceit by the auxiliary transmitter 122, without modifying the telephonecircuit of the interior telephone system in any other Way. This isaccomplished as follows:

As the bell crank lever 260 of the control switch S is rotated in acounterclockwise direction when the actuating rod 266 is depressed, theroller 258 moves upwardly, thereby permitting spring contacts 254 and256 to separate and thus interrupt the'circuit through the transmitter12. At the same time. the roller 258 forces spring contact 252 intoengagement with spring contact 250 to establish a branch circuit fromstationary contact 282 of control switch 214 through conductor 352,transmitter 122, conductor 354, spring contacts 256 and 252 andconductor 356, which joins conductor 334. In this way the party atstation A' is acoustically connected to the public telephone systemthrough the coupling device C and is enabled to converse with theoutside party in the usual manner.

In the event that the conversation is a relatively short one and iscompleted before the timing and switching device TS' completes itscycle, no further manipulation of the equipment is necessary, and thetiming and switching device TS' will eventually interrupt the variouscircuits in the manner already described. However, if the signal bell|26 is automatically actuated just prior to the normal termination ofthe operation of the timing and switching device, the party at station Bmay initiate another cycle of operations in any of the ways previouslydescribed. Moreover, by suitably locating signal bell I 26' within thecabinet at station B', the sound signal produced thereby will be pi kedup by the auxiliary transmitter 122, and will therefore also be heard bythe party at station A', so that he may initiate a new cycle in any ofthe usual ways if he so desires.

Of course, the operator at station B is enabled to hear the conversationby means of the loudspeaker 62 and the receiver 2I8 of the Frenchtelephone instrument F, by reason of their acoustical relation with thetransmitter 220 of the French telephone instrument F and the transmitter122, respectively. When the conversation has been completed, theoperator at station B will therefore be aware of the fact and will thenremove the French telephone instrument F from the acoustical couplingdevice C and restore it to its cradle on the telephone set T.

In so doing the spring 212 associated with the control switch S willrestore the actuating rod 266 and the various spring contacts of thecontrol switch S to their normal positions.

As the to depress the actuating rod 266 French telephone instrument F isagainplaced in its cradle, the total weight of the telephone set T willbe suflicient to lower the floating platform 222 and disengage thecooperating spring contacts 230 and 234, whereby the signal device 3 andthe holding magnet 290 are deenergized and cease to function, thusrestoring the entire system to its normal condition in which it is inreadiness for whatever service that it may be subsequently called uponto render.

In describing the operation of the system oi. Fig. 3, it has beenassumed that station A is located in the office of a superior, forinstance, a business executive, and station B is located in the oiliceof his private secretary or, assistant, and this relationship oistations will be found of great convenience and well adapted to manybusiness organizations. However, in some organizations it may be foundmore advantageous to reverse the location of stations, thus having thepublic telephone set T. and acoustical coupling device C located in theoilice of the executive, in which case he is in a position to have fullknowledge of all outside telephone conversations and may relay suchcalls as he sees fit to his subordinate.

While I have shown and described my invention as embodying more or lessspecific details of construction, operation and arrangements of partsand circuit connections, it will be understood that many variations ormodifications thereof may be made without departing from the spirit andscope of my invitation, and therefore only such limitations should beimposed as are indicated in the appended claims.

I claim as my invention:

l. An interior telephone system comprising in combination, a telephonecircuit adapted to interconnect two stations and including a transmitterand a loud-speaker at each station, a motor-driven timing and switchingdevice for initially establishing said telephone circuit andautomatically interrupting said circuit after a predetermined timeinterval and control means under the control of the operator at-one ofsaid stations for connecting the driving motor to a source of power.

2. An interior telephonesystem comprising in combination, atelephonecircuit adapted to interconnect two stations and including atransmitter and a loud-speaker at each station, a motor-driven timingand switching device for establishing and maintaining said telephonecircuit for a predetermined time interval and subsequently interruptingsaid circuit, and means including a iioating diaphragm capable of motionwhen blown upon by the operator at one of said stations for connectingthe driving motor to a source of power.

3. An interior telephone system comprising in combination, a telephonecircuit adapted to interconnect two stations and including a transmitterand a loud-speaker at each station, means including a timing andswitching device for establishing said telephone circuit for apredetermined time period and then interrupting said circuit, controldevices, including a set of cooperating electrical contact members,located at each station and each adapted to respond to a current ofblown air for eii'ecting electrical engagement of the cooperatingcontact members associated therewith, and means rendered operative whenany set of said contact members is brought into electrical engagementyfor effecting the operation of said timing and switching device.

4. An interior telephone system comprising in combination, a telephonecircuit adapted to interconnect two stations and including aytransmitter and a loud-speaker at each station, a motor-driven timing..and switching device for initially establishing and maintaining saidtelephone circuit for a predetermined time interval and subsequentlyinterrupting -said circuitan electromagneticrelay switch for connectingthe driving motor to a source of power, and means under thecontrol ofthe operator at one of saidI stations for momentarily energizing saidelectromagnetic relay switch for initiating the operation thereof.

5. An interior telephone system comprising in combination, a telephonecircuit adapted to interconnect two stations and including' atransmitter and a loud-speaker at each station, a motor-driven timingand switching device for establishing and maintaining said telephonecircuit for a predetermined time interval and subsequently interruptingsaid circuit, control means including a floating diaphragm adapted to bemoved by blowing upon it and cooperating rela.- tively movable contactsadapted to be momentarily engaged when the diaphragm is so moved, meansincluding an electromagnetic relay switch adapted to be operated whensaid diaphragm contacts are momentarily engaged for connecting thedriving motor to a source of power and means associated with said relayswitch for holding said relay switch in operative position subsequent tothe momentarily engagement of the diaphragm contacts.

6. A system of telephonie communication comprising in combination, atelephone circuit adapted to interconnect two telephone stationsandincluding a transmitter and a loud-speaker at each station, meansincluding a motor-driven timing and switching device adapted to supplypower to the driving motor and to initially establish said telephonecircuit in the order mentioned and after a predetermined period of timeto cut off the supply of power to said motor and interrupt saidtelephone circuit, and means operable at either station for initiallysupplying power to the driving motor.

7. An interior telephone system comprising in combination, a telephonecircuit adapted to interconnect two stations and including a transmitterand a. loud-speaker at each station, a motor-driven timing and switchingdevice for establishing and maintaining said telephone circuit for apredetermined time interval and subsequently interrupting said circuit,an electromagnetic relay switch for connecting the driving motor to asource of power, means for momentarily energizing said electromagneticrelay switch for initiating the operation of said relay switch, andmeans dependent upon said motor-driven timing and switching device forbridging said relay switch to maintain the supply of power to said motorand then interrupting the energizing circuit of said electromagneticrelay switch prior to the establishment of said telephone circuit, andafter a predetermined time interval interrupting the power circuit ofthe driving motor when the telephone circuit is interrupted.

8. A system of telephonie communication comprising in combination, atelephone circuit adapted to interconnect two telephone stations andincluding a transmitter and a loud-speaker at each station, and meansunder the control of the party at either station for initiallyestablishing said telephone circuit for a predetermined time intervaland then automatically interrupting said circ-uit at the end thereof,means for progressively indicating at one of said stations' the elapsedtime and means for eiecting the operation of a signal at one of saidstations shortly prior to the end of said time interval.

9. An interior telephone system comprising in combination, a telephonecircuit adapted to interconnect two stations and including a transmitterand a loud-speaker at each station, a motor-driven timing and switchingdevice for establishing said telephone circuit and automaticallyinterrupting said circuit after a predetermined time interval, controlmeans for connecting the driving motor to a source of power, and meansassociated with said motor-driven timing and switching device forindicating the previous use thereof after its cycle of operation hasbeen completed.

10. In a system of control, the combination of an electromagneticallyoperated device having an energizing winding, a source of electricalenergy, means for momentarily connecting the/energizing winding of saidelectromagnetically operated device to the source of electrical energy,and means operated by the momentary energization of said winding forinsuring the maintenance of such energization after said connectingmeans has ceased to function.

11. In a system of control, the combination of an. electromagnetic-allyoperated device, a floating diaphragm capable of movement when blownupon, electrical means associated with said diaphragm and adapted to beoperated momentarily when actuated thereby for effecting theenergization of said electromagnetically operated device, and meansassociated with said electromagnetically operated device and operable atthe moment of its energization for establishing a holding circuittherefor at themoment of its energization.

12. An interior telephone system comprising in combination, a telephonecircuit adapted to interconnect two telephone stations and including atransmitter and a loud-speaker at each station, a motor-driven timingand switching device for establishing said telephone circuit andautomatically interrupting said circuit after a predetermined timeinterval, control means for initially connecting the driving motor to asource of power, and manually operated means associated with said timingand switching device and independent of said control means for causingsaid timing and switching device to establish said telephone circuitwithout connecting the driving motor to the source of power.

13. An interior telephone system comprising in combination, a telephonecircuit adapted to interconnect two telephone stations and including atransmitter and a loud-speaker at each station, a motor-driven timingand switching device for establishing said telephone circuit andautomatically interrupting said circuit after a predetermined timeinterval, control means for initially connecting the driving motor to asource of power, and manually operated means associated with saidtimingand switching device and independent of said control means andadapted to occupy two operating positions, the one for establishing andmaintaining the telephone circuit while the driving motor of the timingand switching device is inoperative, and the other for connecting thedriving motor to the source of power to effect the operation of saidtiming and switching device.

14. A system of telephonie ommlllliatn 00mprising in combination, apublic telephone system having a French type telephone instrument, aninterior telephone system comprising a telephone circuit adapted tointerconnect two telephone stations and including a transmitter and aloudspeaker at each station, means under the control of the operator atone of said stations for establishing and maintaining said telephonecircuit for a predetermined period of time and then automaticallyinterrupting said circuit and means for effecting an acoustical couplingbetween said interior telephone system and the French type telephoneinstrument of said public telephone system.

15. A system of telephonie communication comprising in combination, apublic telephone system having a French type telephone instrument, aninterior telephone system comprising a telephone circuit adapted tointerconnect two telephone stations and including a transmitter and aloud-speaker at each station, means under the control of the operatorfor establishing and maintaining said telephone circuit for apredetermined period of time and then automatically interrupting saidcircuit, an acoustical coupling device at one of said stations andincluding an auxiliary transmitter and the loud-speaker at said stationwith which the telephone instrument of said public telephone system isplaced in acoustical relation, and a control switch for opening thetelephone circuit through the first-named transmitter at said stationand connecting said auxiliary transmitter in said telephone circuit inplace thereof.

16. A system of telephonie communication comprising in combination, apublic telephone system having a desk type telephone set provided with abase and a French type telephone instrument normally restlngi thereon,an interior telephone system interconnecting two telephone stations andincluding a transmitter and a loud-speaker at each station, means foreffecting an acoustical coupling between said interior telephone circuitand said French type telephone instrument, automatic control meansresponsive to the weight of said telephone set and including anelectromagnetic device adapted to be energized when the French telephoneinstrument is removed from its base and to be deenergized when it isrestored thereto, and a switching device normallyffbiased to anoperative closed position to complete said telephone circuit, butadapted to be manually operatedyinto open position to render saidtelephone circuit inoperative and prevent it from picking upconversation over said French type telephone instrument when in ordinaryuse, said switching device being so disposed with respect to saidelectromagnetic device as to be out of the influence thereof when inclosed operative position but to be electromagnetically telephoneinstruments, a,

instrument located adjacent the transmitter and loud-speaker at one ofthe interior telephone stations, manually operated swltching meanslocated at such station for open-circuiting said interior telephonecircuit when the public telephone system is in ordinary use, andautomatic means dependent upon the weight of said public telephone deskset for holding said switching means in open-circuiting position whensaid public telephone system is in use and for subsequently returning itto its closed circuit position when said French type telephoneinstrument is restored to its base.

18. A system of telephonie communication comprising in combination, apublic telephone system including a controllable amplifier type oftelephone desk set having a French type telephone instrument, aninterior telephone system including a telephone circuit interconnectingtwo stations and including a transmitter and a receiver at each station,and means for effecting an acoustical coupling between the French typetelephone instrument and the transmitter and receiver at one of thestations of the interior telephone system.

19. A system of telephonie communication comprising in combination, apublic telephone system having a French type telephone instrument, aninterior telephone system including a telephone circuit adapted tointerconnect two stations and having a transmitter and a loudspeaker ateach station, timing and switching means for establishing andmaintaining said interior telephone circuit for a predetermined periodof time and then automatically interrupting said circuit, means foracoustically coupling the French telephone instrument and the telephonecircuit of said interior telephone system, and controllable electronicamplifying means for intensifying incoming electrical waves to renderspeech conveniently audible to theY listener on the interior telephonesystem.

20. An interior telephone system comprising in combination, a telephonecircuit adapted to interconnect two telephone stations and including atransmitter and a loud-speaker at each station. automatic means theoperation of which is capable of being initiated by the operator ateither station for first establishing said telephone circuit, thenmaintaining its establishment for a predetermined period of time andthereafter interrupting said telephone circuit, and auxiliary meanscapable of operation before the termination of said time period haselapsed for preventing the interruption of said telephone circuit andmaintaining its establishment for another like time period andthereafter automatically eifecting its interruption.

21. An interior telephone system comprising in combination, a/telephonecircuit adapted to interconnect two telephone stations and including atransmitter and a loud-speaker at each station, automatic means theoperation of which is capable of being initiated by the operator ateither station for first establishing said telephone circuit, thenmaintaining its establishment for a predetermined period of time andthereafter interrupting said telephone circuit, auxiliary means capableof operation before the termination of said time period has elapsed forpreventing the interruption of said telephone circuit and maintainingits establishment for another like time period and thereafterautomatically effecting the interruption, and means for giving a warningsignal prior to the termination of said predetermined time period toenable the operation to be prolonged beyond said predetermined timeperiod.

22. An interior telephone system comprising in combination, a telephonecircuit adapted to interconnect two stations and including a transmitterand a loud-speaker at each station, a motor-driven timing device adaptedto perform a definite cycle in a predetermined time period, switchingmeans mechanically operated by said motor-driven timing device forinitially establishing said telephone circuit between said stations and,after mantaining said circuit for a predetermined time period, effectingthe interruption thereof, and means under the control of the operator ateither station for connecting the driving motor to a source of power toinitiate the operation thereof.

23. An interior telephone system comprising in combination, a telephonecircuit adapted to interconnect two stations and including a transmitterand a loud-speaker at each station, manually operable electrical controlmeans located at each station for effecting a momentary electricalengagement and automatic means responsive to said momentary electricalengagement of said electrical means at either station for initiallyestablishing said telephone circuit between said stations and, after apredetermined period of time. effecting its interruption.

24. A system of telephonie communication comprising in combination, apublic telephone system having a telephone instrument, an electricallyindependent interior telephone system having an operators stationadjacent said public telephone instrument and comprising a telephonecircuit adapted to be connected between said operators station and abranch station of said interior telephone system and including atransmitter and a loud-speaker at each station. means under the controlof the operator at said operators station for acoustically coupling thepublic telephone instrument with said interior teleph^ne system, andmeans under the control of the operator at the operators station forautomatic connection of said interior telephone circuit and itssubsequent disconnection after a predetermined time period, and manualmeans independent of said automatic means for temporarily establishingsaid telephone circuit.

RICHARD VARLEY.

initiating the

